This is a continuation of Application No. PCT/EP2004/006331, filed on Jun. 11, 2004, designating the U.S.
The present invention concerns a method for predicting the wear of at least one tire fitted to a terrestrial motor vehicle, and a wear prediction system for implementing the method. The invention is applicable to any type of automobile vehicle, whether a passenger car, heavy vehicle or construction machinery, and to any two-wheeled vehicle of the motorcycle type.
It is known to predict the wear of a tire fitted to an automobile vehicle by taking into account at the same time the way the vehicle is used during driving (i.e. how ‘hard’ it is driven), the specific characteristics of the vehicle and those of the tire, from the article “Evaluation of Tire Wear Performance, Olivier Le Maître, Manfred Süssner, Cesar Zarak—Society of Automotive Engineers (SAE) Technical Paper Series 980256, pp. 46-47 (International Congress and Exposition, Detroit, Mich., Feb. 23-26, 1998)”.
To estimate how hard the vehicle is driven, the longitudinal and transverse accelerations at the vehicle's centre of gravity are measured at each wheel rotation (or as a function of time), and the sum of the acceleration information obtained is then stored in a matrix.
This acceleration information is used to obtain information representative of the forces and attitudes at the wheel centers of the vehicle's mounted assemblies (such as the longitudinal forces Fx, transverse forces Fy and vertical forces Fz, the slip and camber angles for each tire and for a combination of transverse and longitudinal accelerations), using a “vehicle” model which takes account of the static adjustments of toe-in and camber, the vehicle's static load conditions, the properties of tire-related forces and torques, and the toe-in and camber variations (due to rolling, pitching, conformity to transverse and longitudinal forces, and the self-alignment couple).
A “tire” model or tire wear model is then used to predict the wear from given conditions applied to the wheel centers (as a function of Fx, Fy, Fz and the slip and camber angles for a given tire).
This wear model takes into account the mechanical specifications of the tire's functions (rigidities of the tread, crown and sidewalls) based on finite element results and on experimental data, and enables the prediction of the local distribution of stresses and the slippage rate in the contact area, from which the tread wear can be predicted.
A purpose of the invention is to propose a new method for predicting the wear of at least one tire whose tread has pattern elements and which is fitted to a terrestrial motor vehicle, and a prediction system for implementing the said method that enables a user, such as the vehicle's driver, to know reliably at any given moment the level of wear on the tire or on all the tires (or how long the residual wear will last or even the residual kilometer running distance that results therefrom), and/or to adapt the piloting of drive-aid systems such as “ABS” (anti-block braking system) or “ESP” (electric programmed stability device) systems as a function of the wear characteristics of the vehicle.